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References and notes
29. Dalgard, L.; Jensen, L.; Lawesson, S. O. Tetrahedron
974, 39, 93.
1
1
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273.
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. Asokan, C. V.; Anabha, E. R.; Thomas, A. D.; Jose, A.
M.; Lethesh, K. C.; Prasanth, M.; Krishnaraj, K. U.
Tetrahedron Lett. 2007, 48, 5641.
30. Ramdas, S. R.; Srinivasan, P. S.; Ramachandran, J.;
Sastry, V. V. S. K. Synthesis 1983, 605.
31. Voss, J. Synthesis of Thioesters and Thiolactones. In
Comprehensive Organic Synthesis; Trost, B. M., Ed.;
Pergamon Press: Oxford, 1990; Vol. 6, pp 435–460.
32. Metzner, P. Top. Curr. Chem. 1999, 204, 127.
1
2
3
4
7
2
3
3. Synthesis of b-Oxodithiocarboxylates; general procedure:
acetophenone 1 (20 mmol) was added to a suspension of
NaH (50% suspension in mineral oil, 1.92 g, 40 mmol) in
DMF/hexane solvent mixture (50 mL, 1:10; hexane bp
40–65 ꢁC). Trithiocarbonate (20 mmol) was added to the
solution and stirred well for 1 h. The reaction formed an
interface between the two layers present in the reaction
mixture. The reaction was exothermic and the reaction
mixture was cooled in a water bath at room temperature.
After 1 h, the reaction mixture was acidified with 1 N HCl
(20 mL). The precipitated dithiocarboxylates 2 were
filtered, dissolved in dichloromethane, dried over anhy-
drous sodium sulfate and the solvent was evaporated to
give the corresponding b-oxodithiocarboxylates in good
yields.
5
6
7
8
9
. Nair, S. K.; Samuel, R.; Asokan, C. V. Synthesis 2001,
573.
. Suma, S.; Ushakumari, N. K.; Asokan, C. V. Phosphorus,
Sulfur Silicon Relat. Elem. 1997, 131, 16.
. Deepa, S.; Viswam, D.; Chandran, P.; Asokan, C. V.;
Joseph, B.; Joseph, B.; Sudharsan, C. S. Chem. Commun.
2002, 736.
1
0. Suma, S.; Asokan, C. V. Synth. Commun. 1996, 26, 847.
1. Suma, S.; Asokan, C. V. Indian J. Chem. 1999, 38 B,
1
1
338.
34. Representative experimental procedure for the synthesis of
1-aryl-2-(5-aryl/alkyl-1,3-oxathiol-2-yliden)-1-ethanones:
NaH (50% suspension in mineral oil, 0.48 g, 10 mmol) was
washed with petroleum ether (bp 40–65 ꢁC) and suspended
in 20 mL of dry toluene. Methyl 3-oxo-3-phenylpropan-
edithioate 2a (1.05 g, 5 mmol) was added and the mixture
was stirred for 15 min. To this phenacyl bromide (5 mmol)
was added and the reaction was stirred at room temper-
ature for 48 h. The reaction mixture was then added to
cold water (50 mL) and extracted with diethyl ether
(3 · 50 mL). The combined organic layer was washed with
1
2. Holmes, J. M.; Lee, G. C. M.; Wijino, M.; Weinkam, R.;
Wheeler, L. A.; Garst, M. E. J. Med. Chem. 1994, 37,
1646.
1
1
1
3. Pinto, I. L.; Jarvest, R. L.; Serafinowska, H. T. Tetra-
hedron Lett. 2000, 41, 1597.
4. Luker, T. J.; Beaton, H. G.; Whiting, M.; Mete, A.;
Cheshire, D. R. Tetrahedron Lett. 2000, 41, 7731.
5. Morrison, J. J.; Murray, M. M.; Li, X. C.; Holmes, A. B.;
Morratti, S. C.; Friend, R. H.; Sirringhaus, H. Synth. Met.
1999, 102, 987.
water (3 · 50 mL), dried (Na SO ) and the solvent was
1
6. Li, X. C.; Sirringhaus, H.; Garnier, F.; Holmes, A. B.;
Morratti, S. C.; Feeder, N.; Clegg, W.; Teat, S. J.; Friend,
R. H. J. Am. Chem. Soc. 1998, 120, 2206.
2
4
removed under vacuum. The residue was column chro-
matographed over silica gel using hexane/ethyl acetate
(20:1) as eluent to give the title compound 3a (0.77 g, 55%)
1
7. Mashraqui, S. H.; Hariharasubrahmanian, H.; Kumar, S.
Synthesis 1999, 2030.
as a yellow crystalline solid, mp, 152–154 ꢁC (C17
H O S
12 2
1
1
8. Prim, D.; Kirsch, G. Synth. Commun. 1995, 2449.
9. Augustine, M.; Rudorf, W. D.; Schimdt, U. Tetrahedron
requires C, 72.83; H, 4.31. Found: C, 72.68; H, 4.33.); mmax
À1
1
(KBr) 1690, 1568, 1480, 1300, 1120, 870 cm ; H NMR
(300 MHz, CDCl ): d 6.66 (1H, s, vinylic), 7.20 (1H, s,
C-4); 7.41–7.49 (6H, m, ArH), 7.66 (2H, d, J = 7 Hz,
1
976, 32, 3055.
0. Rehwald, M.; Gewald, K.; Bottcher, G. Heterocycles
997, 45, 493.
1. Ingate, S. T.; Marco, J.; Witvrouw, M.; Pannecouque, C.;
Clercq, E. D. Tetrahedron 1997, 53, 17795.
3
2
2
2
1
3
1
ArH), 7.98 (2H, d, J = 7 Hz, ArH);
(100.40 MHz, CDCl ): d 99.62, 124.90, 127.36, 127.48,
27.88, 128.42, 128.99, 129.50, 131.71, 138.40, 150.48,
C
NMR
3
1
+
2. Tokitoh, N.; Suzuki, T.; Itami, A.; Goto, M.; Ando, W.
Tetrahedron Lett. 1989, 30, 1249.
175.92, 186.43; EI-MS m/z: 280 (M , 99%), 203 (67), 134
(48), 105 (83), 77 (100).